Improvement in safety-guard foe looks



WILLIAM o. sINoLAIR, oF NEW YORK, NY.

Letters Patent No. 82,444, dated September 22, V1868; an'tedateol September 18, 1868.

IMPROVEMENT IN SAFETY-GUARD POR LOCKS.

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TO ALL-'WHOM IT MAY CONCERN:

Be York, have invented a new and useful Improvement in Locks; and I do hereby declare that the following is a full, clear, and exact description thereof,.which will enable those skilled in the art to make and usethe same, reference being had to the accompanying drawing, forming part of this specification, in which drawing- Figure 1 represents an elevation of the working-parts of the lock.

' Figure 2 is a. face view of the lock, showing the protecting-plate of the key-holes.

Similar letters indicate corresponding parts. l

This invention relaties to a lock which is`provided with two key-holes, one from the inside and the other from the outside of the door, said key-holes being separated `from each other by a partition in such a. manner that when the key is in the inside of the lock, it cannot' be reached by any instrument introduced through the key-hole on the outside. On the bolt is a projection, andI if the bolt is locked from the inside, the key strikes' a stop and bears against the projection of the holtin such a manner that said bolt cannot he pushed back by a key or other instrument inserted through the outside keyfhole. On the outside plate of the lock, and pro,-`

tected by .a suitablershield, is an oscillating plate, which is moved by a latch with a cam-groove, whenever the bolt is thrown forward from the inside, in such a manner that the key-holes in the outside plate of the lock are closed, while said oscillating plate remains stationary, if the bolt is locked from the outside.

A represents the case of my lock, which is made of cast iron, or any other suitable material. Through the front plate of this case project the latch B and the bolt C, and in the outside platel of said case are two key-holes a b, (see fig. 2,) While in the insideplate is only one key-hole c, (see iig. 1.) The key inserted through the key-hole a, serres to operate the Vlatch from the outside, while the key inserted through the hole c, serves to lock the bolt from the inside. V The holes b e are not opposite to each other, as in locks 'of the ordinary construction, hut vthey are at diierent distances from the front plateof the lock, as shown in g. 1, and they are separated from each other by a partition, d, so that the key inserted through the hole e cannot be reached-by an instrument inserted through the hole 6. v

When the key is inserted through the inside hole c, and turned to the position shown inl g. 1, it y'strikes a stop, e, and bears against a. projection,f, on the bolt, so that said bolt cannot he throirn Vback by a key or other instrument insertedl through the hole b from the outside. The ,key itself` forms a safeguard against picking the lock. On the outside plate of the case is secured a plate, g, which oscillates on a pivot, 7L, and from which projects a pin, z', through a slot in the plate of the case. When the bolt is locked by the key from the inside, the pin z' is caught by an inclined4 cam-slots), on the latch lc, which is secured to the bolt, and moves with the same, and :which is so arranged that it is raised as the key is turned, so `that the cam-slot will catch the pin. If the bolt is locked from the outsideby inserting the key through the hole b, the latch c isnot raised, and the cam-slot does not catch the pin 2'.' I

By the action of the cam-slot on' the pin z', the plate y is made to oscillate on its pivot t, and' it is brought in such a position, that it covers the h cles a b in the'outer plate oflthc case. If this ,plateg is used, the stop e and projectionfcan be dispensed with, since, by said plate, the introduction ot any key or other instrument from the outside is prevented.

The plate gis protected by a shield, which'is secured to the outer plate of the case, at such a distance from the same, that it allows the plate g to oscillate freely under it. Said shield is provided with holes correspondy ing in position to the holes a 6 so that when the oscillating plate g is`turned hack to the position shown` in fig. 2, the latch-key, and also the key for locking the bolt, can be introduced from the outside. i

What I claim as new, and desire to secure by Letters Patent, isl, The oscillating plate g, having a projecting pin, z', in combination with the cam-slotj on'ithe latch 7c, substantially as and for the purpose described.

WILLIAM C. SINCLAIR.

Witnesses:

W. HAUFF, GUsrAv BERG, 

